Questions tagged [circuit-analysis]

Circuit (Network) analysis is the process of finding the voltages across, and the currents through, every component in the network.

870 questions with no upvoted or accepted answers
Filter by
Sorted by
Tagged with
6 votes
0 answers
163 views

What textbook is this problem from? (circuit analysis)

A somewhat unusual question: Some years ago, the following problem appeared in a test I took during my Bachelor's in electrical engineering. Later, the professor told us which textbook he took it from,...
  • 61
4 votes
0 answers
100 views

Can this Raspberry Pi UPS circuit work?

I created following UPS circuit to shutdown my Raspberry Pi 3A+ properly: I would really appreciate if somebody can review my circuit. I know it's a little bit hard to read, but I'm sorry. I'm a ...
4 votes
0 answers
105 views

Why is the imaginary part absent in the BJT gain calculation?

The gain of transistor Q1 was previously calculated in this post simulate this circuit – Schematic created using CircuitLab It was found to have a gain of about 2.92. Now I change the ...
  • 607
4 votes
2 answers
116 views

automatic submersible pump actuation project

I have a project for automatic submersible pump actuation using a microcontroller. I've done for two voltages like 5 V and 12 V and its corresponding relay. Also, in each board there is a transistor ...
4 votes
1 answer
2k views

Power stage for VCR (Voltage Controlled Resistor)

I'm building a VCR (Voltage Controlled Resistor) using the LM13700 component. You can read more details on that here: Floating voltage-controlled resistor with LM13700: How does it work? The problem ...
  • 2,277
3 votes
0 answers
68 views

Why is each time constant in this transfer function equal to "open circuit" time constant not "short circuit" time constant?

From this lecture notes, the open circuit time constant approximation: How to prove the yellow part? The lecture note mentioned Richard Adler at MIT did prove this but I could not able to find his ...
  • 1,651
3 votes
1 answer
72 views

Capacitor current in parallel network with ESR and parallel resistance

So this might be a very simple question and I've got a knot in my brain but I've been at this for days and don't see how I could solve this problem. I'm trying to find the solution for both ucA, ucB(t)...
3 votes
1 answer
138 views

How to compare Matlab/Theory <=> Cadence: Switched-cap. Integrator: Mag & Phase

I tried to compare the simple switched-capacitor integrator below, between Cadence and Matlab (at the end acting as a simple loop-filter for a delta-sigma). I am stuck now on the point of how to ...
3 votes
2 answers
138 views

Need help with an IR demodulation circuit

I'm trying to reverse engineer a PCB and made a schematic. The bad thing is I only have PCB images from both sides, not the actual PCB. This PCB is used to detect a very small black object spinning at ...
3 votes
1 answer
325 views

Where does the 1V voltage come from?

I have a four PLC with many digital I/O connected similarly to the schematic below. If I use multi meter and measure the voltage between the two points in the schematic, why is it showing 1V? Isn't it ...
3 votes
1 answer
2k views

How do determine MOSFET parameters in LTSPICE

I am designing a phase locked loop on LTspice (which I'm new to), but have come across a snag in the procedure: Is there a way to determine the output resistance of a mosfet (as the I'm not able to ...
3 votes
2 answers
718 views

Intuition on Thevenin's Theorem

In the following lecture by Prof. Anant Agarwal at 36:00, he intuitively proves Thevenin's Theorem using the following circuit simulate this circuit – Schematic created using CircuitLab If ...
3 votes
1 answer
335 views

How do I calculate limit frequency of the attenuator circuit?

Calculate the limit frequency \$fg\$ of the attenuation \$v_u =\frac{ u_a} { u_e}\$ at the current source I (for the value given in example), so that for \$f>> fg\$ exist ideal behavior. Note: ...
3 votes
1 answer
251 views

Is state variable analysis used much in circuit analysis these days?

I am an older EE and I have used the old tried and true methods of circuit analysis like KVL, KCL and some Signal Flow Graph methods. Recently I have been reading about methods that were originally ...
3 votes
0 answers
179 views

Appoximation of a transient response of a more complex circuit

I have a "complicated" circuit that I want to approximate as a simple harmonic oscillator. More info below. I have a parallel LRC circuit, with some extra input and output load resistors and coupling ...
2 votes
0 answers
52 views

About MOSFET circuit behavior

When I look at the waveforms of simulated circuits, how do I know when their behavior (for example flipping value stored on a node, or an unexpected drop in strong level value...) is due to MOSFET ...
2 votes
0 answers
35 views

Sensitivity of Inrush Current Circuit

I'm new to LTSpice and analog design - I'm having a bit of a struggle getting a feel for the behavior of this inrush limiting circuit. Stole the design from another SE post, but playing with the ...
2 votes
0 answers
44 views

RHP pole of two stage OTA

I learnt that for any amplifier (with some capacitor) if we short/open the capacitor and the polarity of gain changes, it is a sign of RHP zero. Now, while applying the same analysis I obsevred that ...
2 votes
0 answers
86 views

Current Direction and Voltage Polarity in Capacitor/Inductor Circuits

I believe that this question may be simple for those with a little more experience, but it is still puzzling me. Studying capacitance/inductance, I understand that the capacitor in the DC case behaves ...
2 votes
0 answers
122 views

Can anyone help me figure out what this circuit does?

I wanted to see if anyone might be able to help me understand this circuit board a bit better. I am trying to trace some issues I'm having with my car stereo and this board is the furthest I can trace ...
2 votes
0 answers
140 views

Small signal analysis of MOSFET circuit

The other day I got the following exercise on one of my exams: For those who don't speak German, for transistor 1 lambda is 0, but not for the others. The backgate-effekt should be neglected ...
2 votes
1 answer
88 views

Finding the mathematical function that describes voltage across diode and resistor circuit

I have the following circuit: simulate this circuit – Schematic created using CircuitLab Where \$\text{V}_\text{i}\left(t\right)=\hat{\text{u}}\sin\left(\omega t+\varphi\right)\$ and the ...
  • 5,491
2 votes
2 answers
125 views

Ideal Transformer Currents Relationship

I'm currently quite confused with the relationship of the currents for an ideal transformer when it overlaps with multiple mesh currents. It was defined that for: $$\frac{\bf I_2}{\bf I_1}=\frac{1}{n}...
  • 21
2 votes
2 answers
76 views

How should fuse selection be made in discrete-time alternating current?

My V(t) signal progresses for hours as 0.75 seconds on,5 seconds off.(Let assume V(t)=I_lamp(t),R_lamp=1 ohm) The general formula for fuse selection at room temperature is: In summary,what should I ...
2 votes
0 answers
148 views

555 PWM circuit set frequency shifting after 2 months

Please refer to post PWM generator circuit review for initial simulation and bugs on the circuit. In general, the circuit works very well and I can control a 12V fan with the PWM output of the 555 ...
  • 131
2 votes
0 answers
183 views

finding state space equation in x=Ax+Bu form

Can anyone please help me to find the state space equation of this circuit diagram in the form of x=Ax+Bu? The equation I am getting is not giving me square matrix. Can anyone help please? These are ...
2 votes
1 answer
62 views

karnaugh table issues

Hello,I have this truth table.I did this table and I am creating a demultiplexer 1 in 2.Not multiplexer. Second,I did and that I gave and those Am I right?I want to confirm that I have done it all ...
  • 95
2 votes
0 answers
531 views

Left half and right half plane zeros

In the common-source on the left, one can solve for the transfer function and see that there's a right-half plane zero at \$s_z = +g_m/C_{gd}\$. For the source-follower on the right, similarly you can ...
2 votes
0 answers
81 views

Nonlinear circuit and RLC

I'm trying to solve the following question from "Communication Circuits: Analysis and Design" by Donald T. Hess: For the circuit shown in Fig. \$1.P1\$, determine an expression for \$v_o(t)\...
  • 127
2 votes
0 answers
188 views

Time delay in lumped element delay line

I was trying to analyse a lumped element-delay line by changing the frequency and measuring \$ V_{in}\$ , as shown in the graph the goal of my analysis is to find the time-delay and the attenuation ...
2 votes
0 answers
74 views

Voltage-divider bias common emitter calculations are yielding unexpected results

I performed an analysis on this voltage-divider-feedback common emitter. My result in simulation is relatively close, but doesn't quite check out. Where did I go wrong? I'm new to this and ...
2 votes
0 answers
69 views

How does this timer 555 and transistor circuit work?

Is this the way this circuit works ? If vref = 5v on the pin #5, then Vthreshold = 5v, and Vtrigger = 2.5v With Vthreshold = 5v, if voltage on pin #6 Vp6 > 5v, then Vp3 is Vo = 0 With Vtrigger = ...
  • 115
2 votes
2 answers
214 views

Voltage Multipler with change capacitor value ratio

I want to ask about Voltage multipler. I understood voltage doubler. By setting the capacitor values ​​of the two capacitors to the same value and setting the voltage doubler circuit, we can obtain a ...
2 votes
0 answers
41 views

Proving the state of a diode in a clamping circuit?

simulate this circuit – Schematic created using CircuitLab So i have this positive clamper right here. So the diode will be ON at a negative source voltage since the anode side will see 5V which ...
's user avatar
2 votes
0 answers
38 views

Adding Line Out / Sub Out to LG soundbar

I have LG Soundbar with wireless sub. I am trying to add Line output, so i could connect a wired sub. I took some pictures of the boards and chips. If someone could point me in right direction on ...
2 votes
0 answers
56 views

How do I find Vs in this circuit with a 2:1 ideal transformer?

How do I find Vs given that V0(to the left) is 10L30degrees? I started by finding that the current on the 10 ohm resistor is 1L30 degrees, and then using kirchoff's law, the current on the tranformer ...
  • 23
2 votes
0 answers
115 views

Need help for pointing out, source follower circuit with current source, designing NMOS

I'm not sure did I solve this problem right. I made \$ r_{o2} \$ , which is resistance looking at Q2 drain. So I can get $$ g_{m,Q3} = 1.8m(A/V) $$ from $$A_v = \frac{r_{o2} || r_{o3}}{1/g_m + (r_{o2} ...
2 votes
1 answer
103 views

How to explain the peak frequency and resistance relationship in this op amp circuit?

I was studying thid tutorial by Simon Bramble. I changed the original circuit a little bit and this is the subject of our discussion: As you see, R1, R2 and R3 are all 1kOhm. When I run an AC ...
2 votes
1 answer
693 views

State-space average model of non-ideal buck converter

I've been learning power electronics and am trying to design a dual-switch forward converter. One of the things I've been trying to do is derive the small-signal equivalent circuit of the non-ideal ...
2 votes
0 answers
49 views

Computing the maximum power that this opamp provides to the load Rl without occurring distortion

Here's the schematic: So first stage is a differential amplifier where vo1 =3.72V in DC (Vin= 0). In this stage i can say AmplVo1 = gainStage1 * AmplVi where distortion only happens when vo1 is ...
2 votes
0 answers
99 views

Problem understanding transfer functions of second order filters

The transfer function of any second order filter can be found by analyzing the circuit using the Laplace transform. For example the transfer function of a second order low pass passive RLC filter ...
2 votes
0 answers
100 views

Are there errors in the description of this circuit?

Background The circuit describes the operation of a variable voltage power supply. In the description below the circuit diagram there are errors. Read through the description and note down any errors....
  • 133
2 votes
0 answers
40 views

Electric power of the light bulbs in a circuit with diodes

Let \$R_1 = 1 \: \Omega, R_2 = 2 \: \Omega, R_3 = 3 \: \Omega, ...R_{10} = 10 \: \Omega\$ be the resistances of the light bulbs depicted in the circuit below and let \$U = 2 \: V\$ be the voltage of ...
2 votes
0 answers
66 views

Trouble understanding how dependent current sources affect a circuit (Two-port networks)

While reviewing a problem from my recent test on two-port networks I noticed that it made its way online. When someone was explaining the solution they utilized a point that I just completely missed. ...
2 votes
0 answers
147 views

First principles modeling of op amp CMRR

Introduction I'm trying to analyze an op amp circuit from first principles (i.e. without using the two rules of ideal op amp analysis -- virtual short circuit and infinite input impedance). The ...
  • 1,462
2 votes
1 answer
105 views

Determining gain, KCL/KWL (Basics)

Below is a pi model schematic of a cascaded amplifier. The goal is to find the gain with Rp as load. So the gain would be: \$ A = \frac{V_{out}}{V_{in}}\$. So i set out to find \$V_{out}\$ in terms ...
  • 31
2 votes
1 answer
245 views

Thermal Noise in Oscillators

let's consider this circuital model for an LC oscillator in which the parasitic resistance R is affected by thermal noise (represented here with an equivalent noise current source, according to the ...
  • 3,276
2 votes
0 answers
131 views

Op-Amps in custom current limiter acting strangely

I'm building a small current limiter (~20 mA). It's important that there is little drop over the current limiter and that the load receives almost the full supply voltage when it's pulling less than ...
2 votes
0 answers
68 views

Circuit Analysis: Difficulty in obtaining a current through a resistor?

I'm solving a problem that requires I compute some impedances, and then the current through a resistor. I obtained some of the impedances*, but don't know how to get the second part (current). ...
  • 209
2 votes
0 answers
132 views

Relationship between base resistor and collector current in this unbalanced differential amplifier

For this BJT circuit, I was wondering if there was a solution for how the collector currents change with respect to the value of the single base resistor. This arrangement popped up in a circuit I ...

1
2 3 4 5
18